TW202019555A - Reactor for the devolatilization of a polymer melt and polycondensation - Google Patents

Abstract

The present invention relates to a reactor for the devolatilization of a polymer melt and polycondensation, comprising a horizontally aligned reactor housing. The reactor housing comprises two end faces and at least one outlet for the devolatilized polymer melt and also at least one vapour port. The reactor of the present invention is characterized in that a horizontally arranged compartmenting element containing a rotor is present in the interior of the reactor housing. The rotor comprises at least one opening bounded by a weir arrangement in the direction of an end face of the reactor housing. The rotor also has a rotor wall impermeable to the polymer melt and divides the interior of the reactor housing into an inner reactor compartment and an outer reactor compartment. In addition, the reactor of the invention comprises a tube which runs through the entry-side end face for introducing the polymer melt. This tube ends in the interior of the rotor, so that the polymer melt is introduced into the inner reactor compartment.

Description

Reactor for devolatilization of polymer melt and polycondensation

Field of invention The present invention relates to a reactor for devolatilization and polycondensation of polymer melts, which comprises a horizontally arranged reactor housing. The reactor housing includes two end faces, and at least one discharge port for the devolatilized polymer melt, and also at least one vapor port. The reactor of the present invention is characterized by the presence of a compartment element arranged horizontally and including a rotating body inside the reactor housing. The rotating body includes at least one opening bounded by the arrangement of the weir body and in the direction of the end face of the reactor housing. The rotor also has a rotor wall that is impermeable to the polymer melt and divides the interior of the reactor housing into an inner reactor compartment and an outer reactor compartment. In addition, the reactor of the present invention includes a tube penetrating the inlet side end surface for introducing the polymer melt. The end of the tube is in the interior of the swivel so as to introduce the polymer melt into the inner reactor compartment.

Background of the invention Since the market demand for polymers is still high, many pre-reactor systems suitable for polycondensation reactors of considerable capacity have been constructed in recent years. In principle, the use of these can produce more popular polymers more cost-effectively. However, further basic development of the polycondensation reactor itself has not yet occurred. In particular, reactors in which the prepolymer melt or polymer melt releases gaseous reaction products and by-products and at the same time post-condensation have not yet been optimally suitable for high throughput.

Conventional reactor structures for post-condensation and devolatilization of polymer melts are known, for example, from EP 0 719 582 A1. This conventional reactor includes an injection port in the lower area for introducing the polymer melt at one end; and an exhaust port for discharging the melt at the other end. After the polymer melt enters the reactor, it can be mixed by a ring element fastened on the rotating assembly of the rotating assembly, and conveyed in the direction of the discharge port. In particular, the gas released here can escape through openings or holes that are assembled as hollow cylinders in the upward direction in the body wall. However, the particular disadvantage of this reactor structure is the high throughput, because in order to ensure the uniformity of the product, a large part of the reactor is still unused, only 18-22% of the total volume of the reactor can be The polymer melt is occupied. Therefore, the reactor must be oversized compared to other equipment components. This side effect is not only during the construction of new polymerization equipment, but also incurs capital costs in the transportation, placement and repair of the reactor, which obviously makes it more difficult.

The reactor of the main content of EP 2 026 903 B1 also has this basic structure described in EP 0 719 582 A1. If a uniform product is to be produced, a large part of the internal space of the reactor also needs to be kept idle.

Summary of the invention Starting from the shortcomings of these devices known in the prior art, the object of the present invention is to improve the structure of the reactor used for subsequent condensation and devolatilization of the polymer melt and to adapt it to changing market demands. A further objective is to provide a method for the devolatilization and polycondensation of polymer melts, which can be used in combination with the modern pre-reactor system of the polycondensation reactor and at high throughput. Finally, the purpose of the method of the present invention is indicated.

These goals with respect to the reactor are achieved by the configuration of claim 1, with respect to the method by the configuration of claim 15 and with regard to the use of the method by the configuration of claim 21. The ancillary items provide excellent concrete examples.

The present invention provides a reactor for devolatilization and polycondensation of polymer melts until the desired polymer chain length has been reached, which includes a horizontally arranged reactor housing, wherein the housing has two end faces, And at least one discharge port for the polymer melt for devolatization, and also at least one vapor port; a compartment element which is horizontally arranged therein and has a rotor, wherein the rotor has a polymer impermeable to the polymer The rotating wall of the melt, wherein the rotating body has at least one opening bounded by the weir body arrangement and in the direction of the end face of the reactor housing and the interior of the reactor housing is divided into an inner reactor compartment and a An outer reactor compartment; and a tube that penetrates the inlet side end face and ends in the interior of the rotor and through which the polymer melt can be introduced into the inner reactor compartment.

The compartment element enables the reactor volume to be used more efficiently, because the interior space of the reactor is divided into at least two reactor compartments arranged rotationally symmetrically around the longitudinal axis of the reactor. The polymer melt can achieve a longer residence time at the same external dimensions. Furthermore, the compartment element makes it possible to obtain a larger surface area inside the reactor, so that if necessary, there are more possibilities to arrange various reactor internal parts in the reactor interior.

At the same time, the reactor of the present invention can reliably prevent the polymer melt from being deposited therein as in conventional reactors. The probability of forming polymer deposits in the inner reactor compartment is low, because first the polymer melt has low viscosity and is fluid when entering the reactor, and secondly it receives continuous rotation. Only if the polymer melt has a higher viscosity in the outer reactor compartment, the risk of polymer deposits there is increased.

The opening bounded by the arrangement of the weirs in the swivel can ensure controlled communication between the inner reactor compartment and the outer reactor compartment, which prevents the polymer melt from being introduced into the reactor After the middle, it directly flows into the outer reactor compartment. The polymer melt can flow from the inner reactor compartment to the outer reactor compartment only when the degree of filling in the inner reactor compartment has reached the minimum level specified by the height of the weir body arrangement Occasionally. Therefore, the size of the weir body arrangement can have an influence on the residence time of the polymer melt.

The rotor assists the devolatization and homogenization of the melt. Due to the rotation of the rotor, the polymer melt will not only be transported horizontally along the longitudinal axis of the reactor but will also undergo tangential acceleration, so that the polymer melt film will be exposed to deeper layers and surface renewal will occur.

The swivel wall of the swivel body is advantageously at least on the inner side, but is preferably equipped with a plurality of transport elements and/or mixing elements on both sides. The transport and/or mixing elements provided on the inner side/both sides of the swivel wall are preferably arranged in an inclined manner. For example, they form an angle range of 60 to 90° or an angle range of 80 to 90° to the swivel wall. The transport and/or mixing elements are preferably offset relative to each other and arranged at the same angle of inclination, so that they can be depicted as stud shapes.

The mixing element makes a major contribution to the surface renewal of the polymer melt film, thus assisting the above mentioned devolatilization and homogenization of the melt. The transport element assists in transporting the melt without residue. The greater the inclination angle of the transport element arrangement, the greater the transport function of the transport element.

Furthermore, the preferred choice of the transport and/or mixing element is the assembly of a tray with circular or polygonal openings, or a structured or unstructured perforated tray with or without scoop elements.

The reactor housing is preferably equipped with a static scraper on the side facing the inside of the reactor housing. In particular, these systems are arranged in the area below the swivel so that they are connected between mixing elements arranged on the outside of the swivel wall. A shearing force is generated between the blade and the mixing element, where the mixing element will extend into the intermediate space between the blades in a comb-like manner during the rotation of the rotor, and this leads to an improvement in the melting of the polymer The body's mobility. In addition, the static squeegee will prevent the layer thickness of the polymer melt on the disc from becoming too large, otherwise this may be due to the polymer melt in the outer reactor compartment in the direction of rotation of the mixing element Occurs when viscosity increases.

The swivel body preferably comprises at least one further weir body arrangement, which is for example arranged in the inner reactor compartment. A particular preference is that the further weir body arrangement is located immediately adjacent to the end of the tube that introduces the polymer melt into the reactor. Advantageously, this further weir arrangement is a weir arrangement that is higher than the boundary opening of the rotor in the direction of the end face of the reactor housing. This further weir arrangement allows the pressure relief of the polymer melt to be controlled. It prevents the polymer melt from being inevitably entrained in the released gas product and spraying the fine droplets formed by the polymer melt when it is introduced into the reactor due to pressure relief.

The rotating body wall may have a cylindrical, truncated cone or double cone shape. In practice, the cylindrical shape and the double cone shape have been found to be particularly useful. The rotor wall assembled in the shape of a double cone defines a defined flow direction for the polymer melt because of its angled surface.

The swivel can be connected to two rotationally assembled drive shaft ends by fastener tools and optionally by a sheath. The fastener tool is preferably selected from the group consisting of spokes, spoke wheels, perforated discs, solid discs and combinations thereof. However, the solid disk is preferably used only for connection to the end of the drive shaft indicated in the direction of the inlet side end face of the reactor housing. On the other hand, the spokes, spoke wheels, perforated discs and combinations thereof are preferably used to fasten the inner rotor to the other end of the transmission shaft. This causes the polymer melt to reside in the inner reactor compartment for a period of time before it goes to the outer reactor compartment.

In the first embodiment of the reactor of the present invention, the tube for introducing the polymer melt extends into the reactor casing to a position of 30 to 70%, preferably 40 to 60% of the length of the reactor . In this specific example, the rotating body preferably has two openings, each of which is in the direction of the two end faces and is bounded by the arrangement of the weir body. In addition, in this specific example, the swivel wall preferably has a double-conical shape.

In a second specific example of the reactor of the present invention, the tube extends into the reactor at least 15% of the length of the reactor, preferably less than 10%, and the swivel is particularly preferably An opening, which is bounded by the weir body arrangement in the direction of the end surface opposite to the inlet side end surface. In this second specific example, it is beneficial that the swivel wall has a cylindrical shape.

Beneficially, the swivel or integral compartment element can be heated. For this purpose, the swivel or compartment element preferably has jacket heating.

Heating the swivel or compartment element by jacket heating prevents the polymer melt from cooling and adhering to the swivel wall or further surface of the compartment element.

However, the various reactors that can be heated by the reactor housing provide still more important advantages. In order to achieve heating, a jacket heating consisting of jacket heating operated by a heat transfer fluid or electric jacket heating may be arranged.

Heating the reactor enclosure also allows the viscosity of the polymer melt in the outer reactor compartment to be increased in a targeted manner to medium to high polymer flow capacity. Therefore, it can be ruled out that the inner reactor elements stick together.

A further preferred configuration of the invention is that the reactor is preferably hermetically sealed from the surrounding air by rotary sealing and/or by a sealing system supplying barrier liquid. The end of the drive shaft can be fitted in the interior of the reactor housing or in a bearing housing connected to the reactor housing.

The length-to-diameter ratio of the reactor housing is preferably 1.1 to 4.0, particularly preferably 1.5 to 3.0, and more preferably 2.5 to 3.0. Furthermore, it is wise to note the size of the rotor when constructing the reactor: the diameter of the rotor should be advantageously selected so that the ratio of the diameter of the rotor to the diameter of the reactor is in the range of 0.5 to 0.7. In addition, the preferred range of the ratio between the length of the rotor and the length of the reactor housing is 0.50 to 0.99, preferably 0.70 to 0.95.

Furthermore, the preference for the at least one discharge port for the devolatilized polymer melt is arranged below the rotor, and the at least one vapor port is arranged above the rotor. The position of the at least one discharge port for the devolatile polymer melt must be selected according to the configuration of the rotor. If the swivel has two openings, it is wise to arrange the at least one discharge port in the center. If the rotating body has only one opening, the at least one discharge port is arranged at the end of the reactor housing opposite to the opening of the rotating body.

This ensures that the polymer melt flow is diverted at least once, and the polymer melt system in the outer reactor compartment travels countercurrent to the polymer melt in the inner reactor compartment.

In order to optimize the further use of the internal space of the reactor, yet another specific example of the reactor in which the compartment element includes another swivel is also provided. This other swivel divides the outer reactor compartment into two sub-compartments. The other swivel is preferably connected to the swivel by the same fastener tool as the end that connects the swivel to the drive shaft.

The invention also provides a method for devolatilization of a polymer melt, wherein the polymer melt system is fed to a reactor according to one of the preceding claims. In this method, the polymer melt is first transported via a tube into a first reactor compartment surrounded by a rotor and transported in the direction in which at least one weir is arranged. The polymer melt is then placed through the at least one weir body and into the outer reactor compartment before leaving the reactor.

The flow direction of the polymer melt in the reactor is preferably reversed at least once, preferably when it is arranged through the at least one weir. When the polymer melt is arranged through the at least one weir or during the transfer from the inner reactor compartment to the outer reactor compartment, its flow can be guided by the turning plate, which keeps the end face from being ineffective space.

In preferred variations of the method, the polymer melt fed to the reactor has an intrinsic viscosity no greater than 0.6 deciliters/gram, particularly preferably no greater than 0.5 deciliters/gram, more preferably 0.25 to 0.35 minutes L/g.

Advantageously, the polymer melt is fed into the reactor by a pump, and then the melt is separated from the first reactor by a rotary conveying element and/or mixing element inclined in the conveying direction Is transported to the at least one further reactor compartment, wherein the rotation speed is preferably 0.5-10 revolutions per minute, particularly preferably 1.0-5 revolutions per minute, and more preferably 1.5-3 revolutions per minute.

Furthermore, it is wise to continuously evacuate the reactor during the process. The preferred pressure inside the reactor is preferably 0.1 to 3.0 mbar, preferably 0.3 to 1.0 mbar. Evacuation will assist the devolatilization of the polymer melt and cause very small amounts of gaseous reaction products and by-products to remain in the product.

Preferably, the temperature of the reactor jacket is brought to 10 to 50°C higher than the melting point of the polymer by jacket heating, particularly preferably 15 to 30°C higher than the melting point of the polymer.

Finally, according to the present invention, it is recommended to use the above method to produce polyesters with an inherent viscosity in the range of 0.6 to 1.0 deciliters/gram, especially PET, with a preferred range of 0.70 to 0.85 deciliters/gram, and a particularly preferred range of 0.72 to 0.82 dl/g.

Polyesters with an inherent viscosity of about 0.64 are suitable for textile applications and for making biaxially oriented polyester films (BO-PET). On the other hand, polyesters with higher inherent viscosity tend to be used to make beverage bottles.

Detailed description of the preferred embodiment FIG. 1 shows a first specific example of the present invention, which provides a central inlet for the polymer melt to enter the reactor. The tube 4 penetrating the inlet side end face 3 extends into the rotating body to approximately the middle. The reactor housing 1 has an approximately cylindrical shape and has end faces 2 and 3. In addition, the reactor housing 1 is assembled into a vacuum container that can be used at a low pressure of 0.1-3.0 mbar or lower. The turning system is arranged concentrically around the longitudinal axis indicated by the dashed line. The rotating body wall 7 has a double cone shape. Where the polymer melt enters the reactor, kinks can be seen in the rotor wall 7, which indicates that one cone crossed into another cone at this point. At its two ends, the rotating system is connected to the drive shaft end 6 via a fastener tool 18. In addition, the swivel body has an opening 8 which is bounded by a weir body 9 directed radially around the circumference at both ends.

The concentrically arranged rotor in the reactor enclosure forms the compartment element, which divides the interior space of the reactor into an inner reactor compartment 20 (in the rotor, "stage 1") and an outer reactor compartment 30 (In the intermediate space between the rotor and the reactor housing, "Stage 2").

In the outer reactor compartment 30, the static scraper 13 is fastened to the reactor housing wall in the area below the rotor. The mixing element 10 attached to the outside of the swivel wall 7 protrudes into the intermediate space between the static blades 13. In addition, the reactor housing 1 has a discharge port 11 below the rotating body. A plurality of steam ports 12 are indicated above the turn.

A plurality of transport and/or mixing elements 10 are fastened to the side of the swivel wall facing the inner reactor compartment 20. For example, these can be assembled into disks that provide circular or polygonal openings, or structured or unstructured perforated disks with or without scooping elements, which are arranged helically or studd on the drive shaft. However, all transport and/or mixing elements have a central recess in order to form a hollow space. This hollow space first provides for the passage of the tube 4. Secondly, it allows the released gas to escape unhindered. The hollow space may also be defined by the delimiting sheath 5, as indicated in the right-hand part of the drawing.

Together with the sheath 5 delimiting the hollow space and the mixing and/or transport element 10, the swivel forms a stable and strong load-bearing structure.

The drive shaft end 6 of the rotating body is also stably assembled. On the inlet side, they are suspended in sliding bearings inside the reactor; on the driving side, they are tied in standard cylindrical roller bearings (bearing pedestals 19 outside the reactor). The bearing block 19 is connected to the reactor housing. A sealing system supplying barrier liquid can be used to seal the drive shaft against the environment. Furthermore, both bearings can also be arranged outside the reactor and a rotary seal can be used (for example, from Christian Maier GmbH & Co. KG, Heidenheim).

Figure 2 shows a reactor according to the invention according to a second specific example. This is different from the first specific example of FIG. 1 first in the tube 4, by which the polymer melt is introduced into the end of the reactor rather than in the middle of the reactor, but only in the total reactor length is only about 10%. In addition, the swivel wall 7 has a cylindrical shape and the swivel is open on only one side. The second side of the swivel directly opposite the entrance side end face 3 is closed by a fastener element 18 assembled as a solid disc. This prevents the polymer melt from directly advancing from the inner reactor compartment 20 into the outer reactor compartment 30 after being introduced into the reactor without coming into contact with the inner mixing and transport element 10. In addition, this specific example of the reactor differs in that the mixing and conveying element 10 disposed in the inner reactor compartment 20 is inclined. Compared with the reactor of FIG. 1, the steam port 12 and the discharge port 11 are also configured differently.

Figure 3 shows the more complex reactors of the present invention, in which the compartment element consists of two rotors. The other turning system is arranged concentrically around the first inner turning body and it likewise has a turning wall 7'impermeable to the polymer melt. In addition, the other rotation system is connected to the first inner rotating body by a fastener tool 18' so as to rotate at the same frequency during operation. The fastener tool 18' may be composed of a flat iron disk, a round iron disk, or a permeable disk. The other rotor divides the outer reactor compartment into two sub-compartments 30' and 30", and causes the flow direction of the polymer melt processed therein to undergo a double reversal. The inner space of the reactor is obtained by The polymer melt is optimally used for the double turns at overflow weirs 9'and 9".

1: Reactor cover 2: end face 3: entrance side 4: Tube 5: Delimited sheath 6: drive shaft end 7,7’: Swivel wall 8: opening 9: Weir body 9’,9”: overflow weir 10: Mixing and/or shipping components 11: discharge port 12: Steam port 13: Static scraper 18,18’: fastener tool 19: Bearing seat 20: inner reactor compartment 30: outer reactor compartment 30’, 30”: sub-compartment

The invention is illustrated with the aid of the following figures, but the invention is not limited by the parameters specifically indicated.

Figures 1 and 2 show a depiction of a reactor with a swivel according to the invention, where the swivel wall has a double-conical shape.

Figure 3 shows a depiction of a reactor with a swivel according to the invention, where the swivel wall has a cylindrical shape.

1: Reactor cover

2: end face

3: entrance side

4: Tube

5: Delimited sheath

6: drive shaft end

7: Swivel wall

8: opening

9: Weir body

10: Mixing and/or shipping components

11: discharge port

12: Steam port

13: Static scraper

18: Fastener tool

19: Bearing seat

20: inner reactor compartment

30: outer reactor compartment

Claims (21)

A reactor for devolatilization and polycondensation of polymer melt to obtain the desired polymer chain length, which comprises: A horizontally arranged reactor housing with two end faces and at least one discharge port for the devolatized polymer melt and also at least one steam port; A compartment element which is horizontally arranged therein and contains a rotor having a rotor wall impermeable to the polymer melt, wherein the rotor has at least one weir body in the direction of the end face of the reactor housing Arranging the defined opening and dividing the inside of the reactor enclosure into an inner reactor compartment and an outer reactor compartment; and A tube which penetrates the inlet side end face and ends in the interior of the rotor and thereby the polymer melt can be introduced into the inner reactor compartment. The reactor according to claim 1 is characterized in that the swivel wall is at least on the inner side, but it is preferably equipped with a plurality of transport elements and/or mixing elements on both sides. The reactor according to the preceding claim is characterized in that the conveying elements and/or mixing elements provided on the inner edge of the rotating wall are arranged in an inclined manner, preferably at an angle of 60 to 90° with respect to the rotating wall. It is preferably 80 to 90°. The reactor according to any one of the preceding two claims, characterized in that the reactor housing is equipped with a static scraper on its inner surface, and it is preferred that they are connected to the mixing element arranged on the outer edge of the rotating body wall This way is arranged in the area below the swivel. A reactor as claimed in any one of the preceding claims, characterized in that the swivel has at least one further weir arrangement, which is preferably arranged in the inner reactor compartment. The reactor according to any one of the preceding claims, characterized in that the rotating body wall has a cylindrical shape, a truncated cone shape or a double cone shape. The reactor according to any one of the preceding claims, characterized in that the rotating system is connected to two drive shaft ends assembled to be rotatable, wherein the connection is preferably established by fastener tools, especially spokes and spoke wheels , Perforated discs and/or solid discs, and optionally through sheaths. A reactor as claimed in any one of the preceding claims, characterized in that the swivel or compartment element can be heated, preferably by jacket heating. The reactor according to any one of the preceding claims, characterized in that the tube extends into the reactor housing to a position of 30 to 70%, preferably 40 to 60% of the length of the reactor, and the rotation is at The two end faces have two openings in the direction, wherein each opening is bounded by a weir arrangement. A reactor as claimed in any one of the preceding claims, characterized in that the tube extends into the reactor at least 15% of the length of the reactor, preferably less than 10%, and the swivel The inlet side end face has an opening in the direction opposite to the end face, wherein the opening is bounded by a weir body arrangement. A reactor as claimed in any one of the preceding claims, characterized in that the reactor housing is heatable, preferably by jacket heating, wherein the jacket heating is a jacket heating or operation using a heat transfer fluid Electric jacket heating. A reactor as claimed in any one of the preceding claims, characterized in that the reactor is preferably a rotary seal and/or a sealing system supplied with barrier liquid and/or by assembling at least inside the reactor housing One drive shaft end is hermetically sealed from the surrounding air. The reactor according to any one of the preceding claims, characterized in that the ratio of the length to the diameter of the outer shell of the reactor is 1.1 to 4.0, preferably 1.5 to 3.0, particularly preferably 2.5 to 3.0. A reactor as claimed in any one of the preceding claims, characterized in that the compartment element comprises a further rotor with a rotor wall impermeable to the polymer melt, which separates the outer reactor The compartment is divided into two sub-compartments, and the other swivel is preferably fastened to the swivel by a fastener tool. A method for devolatilization of a polymer melt, in which a polymer melt system is fed to the reactor according to any one of the preceding claims; and The polymer melt system is transported via a tube into a first reactor compartment surrounded by a rotor; Then transport in the direction of at least one weir body arrangement; Through the at least one weir body arrangement; and Before leaving the reactor, go to at least one outer reactor compartment. The method of claim 15, characterized in that the flow direction of the polymer melt before leaving the reactor is preferably reversed at least once when passing through the at least one weir body. The method according to claim 15 or 16, characterized in that the feed polymer melt has an inherent viscosity of not more than 0.6 deciliters/gram, preferably not more than 0.5 deciliters/gram, particularly preferably from 0.25 to 0.35 deciliters /G. The method according to any one of claims 15 to 17, characterized in that the polymer melt system is fed to the reactor by a pump, and by rotating conveying elements and/or mixing elements inclined in the conveying direction Transport from the first reactor compartment to the at least one further reactor compartment, wherein the rotation speed is preferably 0.5-10 revolutions per minute, particularly preferably 1.0-5 revolutions per minute, more preferably 1.5-minutes per minute 3 turns. The method according to any one of claims 15 to 18, characterized in that the reactor is continuously evacuated so that the pressure within the reactor is preferably preferably 0.1 to 3.0 mbar, preferably 0.3 to 1.0 mbar . The method according to any one of claims 15 to 19, characterized in that the reactor jacket is maintained by a jacket heating at a temperature higher than the melting point of the polymer by 10 to 50°C, preferably higher than that of the polymer Melting point 15 to 30°C. Use of a method according to any one of claims 15 to 20, which is used to prepare polyethylene terephthalate (PET) having an intrinsic viscosity in the range of 0.6 to 1.0 deciliter/gram, preferably in the range of 0.70 to 0.85 deciliters/gram, the particularly good range is 0.72 to 0.82 deciliters/gram.

Images